therm_pm72.c

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/*
 * Device driver for the thermostats & fan controller of  the
 * Apple G5 "PowerMac7,2" desktop machines.
 *
 * (c) Copyright IBM Corp. 2003-2004
 *
 * Maintained by: Benjamin Herrenschmidt
 *                <[e-mail]>
 * 
 *
 * The algorithm used is the PID control algorithm, used the same
 * way the published Darwin code does, using the same values that
 * are present in the Darwin 7.0 snapshot property lists.
 *
 * As far as the CPUs control loops are concerned, I use the
 * calibration & PID constants provided by the EEPROM,
 * I do _not_ embed any value from the property lists, as the ones
 * provided by Darwin 7.0 seem to always have an older version that
 * what I've seen on the actual computers.
 * It would be interesting to verify that though. Darwin has a
 * version code of 1.0.0d11 for all control loops it seems, while
 * so far, the machines EEPROMs contain a dataset versioned 1.0.0f
 *
 * Darwin doesn't provide source to all parts, some missing
 * bits like the AppleFCU driver or the actual scale of some
 * of the values returned by sensors had to be "guessed" some
 * way... or based on what Open Firmware does.
 *
 * I didn't yet figure out how to get the slots power consumption
 * out of the FCU, so that part has not been implemented yet and
 * the slots fan is set to a fixed 50% PWM, hoping this value is
 * safe enough ...
 *
 * Note: I have observed strange oscillations of the CPU control
 * loop on a dual G5 here. When idle, the CPU exhaust fan tend to
 * oscillates slowly (over several minutes) between the minimum
 * of 300RPMs and approx. 1000 RPMs. I don't know what is causing
 * this, it could be some incorrect constant or an error in the
 * way I ported the algorithm, or it could be just normal. I
 * don't have full understanding on the way Apple tweaked the PID
 * algorithm for the CPU control, it is definitely not a standard
 * implementation...
 *
 * TODO:  - Check MPU structure version/signature
 *        - Add things like /sbin/overtemp for non-critical
 *          overtemp conditions so userland can take some policy
 *          decisions, like slewing down CPUs
 *	  - Deal with fan and i2c failures in a better way
 *	  - Maybe do a generic PID based on params used for
 *	    U3 and Drives ? Definitely need to factor code a bit
 *          bettter... also make sensor detection more robust using
 *          the device-tree to probe for them
 *        - Figure out how to get the slots consumption and set the
 *          slots fan accordingly
 *
 * History:
 *
 *  Nov. 13, 2003 : 0.5
 *	- First release
 *
 *  Nov. 14, 2003 : 0.6
 *	- Read fan speed from FCU, low level fan routines now deal
 *	  with errors & check fan status, though higher level don't
 *	  do much.
 *	- Move a bunch of definitions to .h file
 *
 *  Nov. 18, 2003 : 0.7
 *	- Fix build on ppc64 kernel
 *	- Move back statics definitions to .c file
 *	- Avoid calling schedule_timeout with a negative number
 *
 *  Dec. 18, 2003 : 0.8
 *	- Fix typo when reading back fan speed on 2 CPU machines
 *
 *  Mar. 11, 2004 : 0.9
 *	- Rework code accessing the ADC chips, make it more robust and
 *	  closer to the chip spec. Also make sure it is configured properly,
 *        I've seen yet unexplained cases where on startup, I would have stale
 *        values in the configuration register
 *	- Switch back to use of target fan speed for PID, thus lowering
 *        pressure on i2c
 *
 *  Oct. 20, 2004 : 1.1
 *	- Add device-tree lookup for fan IDs, should detect liquid cooling
 *        pumps when present
 *	- Enable driver for PowerMac7,3 machines
 *	- Split the U3/Backside cooling on U3 & U3H versions as Darwin does
 *	- Add new CPU cooling algorithm for machines with liquid cooling
 *	- Workaround for some PowerMac7,3 with empty "fan" node in the devtree
 *	- Fix a signed/unsigned compare issue in some PID loops
 *
 *  Mar. 10, 2005 : 1.2
 *	- Add basic support for Xserve G5
 *	- Retreive pumps min/max from EEPROM image in device-tree (broken)
 *	- Use min/max macros here or there
 *	- Latest darwin updated U3H min fan speed to 20% PWM
 *
 *  July. 06, 2006 : 1.3
 *	- Fix setting of RPM fans on Xserve G5 (they were going too fast)
 *      - Add missing slots fan control loop for Xserve G5
 *	- Lower fixed slots fan speed from 50% to 40% on desktop G5s. We
 *        still can't properly implement the control loop for these, so let's
 *        reduce the noise a little bit, it appears that 40% still gives us
 *        a pretty good air flow
 *	- Add code to "tickle" the FCU regulary so it doesn't think that
 *        we are gone while in fact, the machine just didn't need any fan
 *        speed change lately
 *
 */

#include <linux/types.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/reboot.h>
#include <linux/kmod.h>
#include <linux/i2c.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/sections.h>
#include <asm/of_device.h>
#include <asm/macio.h>
#include <asm/of_platform.h>

#include "therm_pm72.h"

#define VERSION "1.3"

#undef DEBUG

#ifdef DEBUG
#define DBG(args...)	printk(args)
#else
#define DBG(args...)	do { } while(0)
#endif


/*
 * Driver statics
 */

static struct of_device *		of_dev;
static struct i2c_adapter *		u3_0;
static struct i2c_adapter *		u3_1;
static struct i2c_adapter *		k2;
static struct i2c_client *		fcu;
static struct cpu_pid_state		cpu_state[2];
static struct basckside_pid_params	backside_params;
static struct backside_pid_state	backside_state;
static struct drives_pid_state		drives_state;
static struct dimm_pid_state		dimms_state;
static struct slots_pid_state		slots_state;
static int				state;
static int				cpu_count;
static int				cpu_pid_type;
static pid_t				ctrl_task;
static struct completion		ctrl_complete;
static int				critical_state;
static int				rackmac;
static s32				dimm_output_clamp;
static int 				fcu_rpm_shift;
static int				fcu_tickle_ticks;
static DECLARE_MUTEX(driver_lock);

/*
 * We have 3 types of CPU PID control. One is "split" old style control
 * for intake & exhaust fans, the other is "combined" control for both
 * CPUs that also deals with the pumps when present. To be "compatible"
 * with OS X at this point, we only use "COMBINED" on the machines that
 * are identified as having the pumps (though that identification is at
 * least dodgy). Ultimately, we could probably switch completely to this
 * algorithm provided we hack it to deal with the UP case
 */
#define CPU_PID_TYPE_SPLIT	0
#define CPU_PID_TYPE_COMBINED	1
#define CPU_PID_TYPE_RACKMAC	2

/*
 * This table describes all fans in the FCU. The "id" and "type" values
 * are defaults valid for all earlier machines. Newer machines will
 * eventually override the table content based on the device-tree
 */
struct fcu_fan_table
{
	char*	loc;	/* location code */
	int	type;	/* 0 = rpm, 1 = pwm, 2 = pump */
	int	id;	/* id or -1 */
};

#define FCU_FAN_RPM		0
#define FCU_FAN_PWM		1

#define FCU_FAN_ABSENT_ID	-1

#define FCU_FAN_COUNT		ARRAY_SIZE(fcu_fans)

struct fcu_fan_table	fcu_fans[] = {
	[BACKSIDE_FAN_PWM_INDEX] = {
		.loc	= "BACKSIDE,SYS CTRLR FAN",
		.type	= FCU_FAN_PWM,
		.id	= BACKSIDE_FAN_PWM_DEFAULT_ID,
	},
	[DRIVES_FAN_RPM_INDEX] = {
		.loc	= "DRIVE BAY",
		.type	= FCU_FAN_RPM,
		.id	= DRIVES_FAN_RPM_DEFAULT_ID,
	},
	[SLOTS_FAN_PWM_INDEX] = {
		.loc	= "SLOT,PCI FAN",
		.type	= FCU_FAN_PWM,
		.id	= SLOTS_FAN_PWM_DEFAULT_ID,
	},
	[CPUA_INTAKE_FAN_RPM_INDEX] = {
		.loc	= "CPU A INTAKE",
		.type	= FCU_FAN_RPM,
		.id	= CPUA_INTAKE_FAN_RPM_DEFAULT_ID,
	},
	[CPUA_EXHAUST_FAN_RPM_INDEX] = {
		.loc	= "CPU A EXHAUST",
		.type	= FCU_FAN_RPM,
		.id	= CPUA_EXHAUST_FAN_RPM_DEFAULT_ID,
	},
	[CPUB_INTAKE_FAN_RPM_INDEX] = {
		.loc	= "CPU B INTAKE",
		.type	= FCU_FAN_RPM,
		.id	= CPUB_INTAKE_FAN_RPM_DEFAULT_ID,
	},
	[CPUB_EXHAUST_FAN_RPM_INDEX] = {
		.loc	= "CPU B EXHAUST",
		.type	= FCU_FAN_RPM,
		.id	= CPUB_EXHAUST_FAN_RPM_DEFAULT_ID,
	},
	/* pumps aren't present by default, have to be looked up in the
	 * device-tree
	 */
	[CPUA_PUMP_RPM_INDEX] = {
		.loc	= "CPU A PUMP",
		.type	= FCU_FAN_RPM,		
		.id	= FCU_FAN_ABSENT_ID,
	},
	[CPUB_PUMP_RPM_INDEX] = {
		.loc	= "CPU B PUMP",
		.type	= FCU_FAN_RPM,
		.id	= FCU_FAN_ABSENT_ID,
	},
	/* Xserve fans */
	[CPU_A1_FAN_RPM_INDEX] = {
		.loc	= "CPU A 1",
		.type	= FCU_FAN_RPM,
		.id	= FCU_FAN_ABSENT_ID,
	},
	[CPU_A2_FAN_RPM_INDEX] = {
		.loc	= "CPU A 2",
		.type	= FCU_FAN_RPM,
		.id	= FCU_FAN_ABSENT_ID,
	},
	[CPU_A3_FAN_RPM_INDEX] = {
		.loc	= "CPU A 3",
		.type	= FCU_FAN_RPM,
		.id	= FCU_FAN_ABSENT_ID,
	},
	[CPU_B1_FAN_RPM_INDEX] = {
		.loc	= "CPU B 1",
		.type	= FCU_FAN_RPM,
		.id	= FCU_FAN_ABSENT_ID,
	},
	[CPU_B2_FAN_RPM_INDEX] = {
		.loc	= "CPU B 2",
		.type	= FCU_FAN_RPM,
		.id	= FCU_FAN_ABSENT_ID,
	},
	[CPU_B3_FAN_RPM_INDEX] = {
		.loc	= "CPU B 3",
		.type	= FCU_FAN_RPM,
		.id	= FCU_FAN_ABSENT_ID,
	},
};

/*
 * i2c_driver structure to attach to the host i2c controller
 */

static int therm_pm72_attach(struct i2c_adapter *adapter);
static int therm_pm72_detach(struct i2c_adapter *adapter);

static struct i2c_driver therm_pm72_driver =
{
	.driver = {
		.name	= "therm_pm72",
	},
	.attach_adapter	= therm_pm72_attach,
	.detach_adapter	= therm_pm72_detach,
};

/*
 * Utility function to create an i2c_client structure and
 * attach it to one of u3 adapters
 */
static struct i2c_client *attach_i2c_chip(int id, const char *name)
{
	struct i2c_client *clt;
	struct i2c_adapter *adap;

	if (id & 0x200)
		adap = k2;
	else if (id & 0x100)
		adap = u3_1;
	else
		adap = u3_0;
	if (adap == NULL)
		return NULL;

	clt = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
	if (clt == NULL)
		return NULL;

	clt->addr = (id >> 1) & 0x7f;
	clt->adapter = adap;
	clt->driver = &therm_pm72_driver;
	strncpy(clt->name, name, I2C_NAME_SIZE-1);

	if (i2c_attach_client(clt)) {
		printk(KERN_ERR "therm_pm72: Failed to attach to i2c ID 0x%x\n", id);
		kfree(clt);
		return NULL;
	}
	return clt;
}

/*
 * Utility function to get rid of the i2c_client structure
 * (will also detach from the adapter hopepfully)
 */
static void detach_i2c_chip(struct i2c_client *clt)
{
	i2c_detach_client(clt);
	kfree(clt);
}

/*
 * Here are the i2c chip access wrappers
 */

static void initialize_adc(struct cpu_pid_state *state)
{
	int rc;
	u8 buf[2];

	/* Read ADC the configuration register and cache it. We
	 * also make sure Config2 contains proper values, I've seen
	 * cases where we got stale grabage in there, thus preventing
	 * proper reading of conv. values
	 */

	/* Clear Config2 */
	buf[0] = 5;
	buf[1] = 0;
	i2c_master_send(state->monitor, buf, 2);

	/* Read & cache Config1 */
	buf[0] = 1;
	rc = i2c_master_send(state->monitor, buf, 1);
	if (rc > 0) {
		rc = i2c_master_recv(state->monitor, buf, 1);
		if (rc > 0) {
			state->adc_config = buf[0];
			DBG("ADC config reg: %02x\n", state->adc_config);
			/* Disable shutdown mode */
		       	state->adc_config &= 0xfe;
			buf[0] = 1;
			buf[1] = state->adc_config;
			rc = i2c_master_send(state->monitor, buf, 2);
		}
	}
	if (rc <= 0)
		printk(KERN_ERR "therm_pm72: Error reading ADC config"
		       " register !\n");
}

static int read_smon_adc(struct cpu_pid_state *state, int chan)
{
	int rc, data, tries = 0;
	u8 buf[2];

	for (;;) {
		/* Set channel */
		buf[0] = 1;
		buf[1] = (state->adc_config & 0x1f) | (chan << 5);
		rc = i2c_master_send(state->monitor, buf, 2);
		if (rc <= 0)
			goto error;
		/* Wait for convertion */
		msleep(1);
		/* Switch to data register */
		buf[0] = 4;
		rc = i2c_master_send(state->monitor, buf, 1);
		if (rc <= 0)
			goto error;
		/* Read result */
		rc = i2c_master_recv(state->monitor, buf, 2);
		if (rc < 0)
			goto error;
		data = ((u16)buf[0]) << 8 | (u16)buf[1];
		return data >> 6;
	error:
		DBG("Error reading ADC, retrying...\n");
		if (++tries > 10) {
			printk(KERN_ERR "therm_pm72: Error reading ADC !\n");
			return -1;
		}
		msleep(10);
	}
}

static int read_lm87_reg(struct i2c_client * chip, int reg)
{
	int rc, tries = 0;
	u8 buf;

	for (;;) {
		/* Set address */
		buf = (u8)reg;
		rc = i2c_master_send(chip, &buf, 1);
		if (rc <= 0)
			goto error;
		rc = i2c_master_recv(chip, &buf, 1);
		if (rc <= 0)
			goto error;
		return (int)buf;
	error:
		DBG("Error reading LM87, retrying...\n");
		if (++tries > 10) {
			printk(KERN_ERR "therm_pm72: Error reading LM87 !\n");
			return -1;
		}
		msleep(10);
	}
}

static int fan_read_reg(int reg, unsigned char *buf, int nb)
{
	int tries, nr, nw;

	buf[0] = reg;